Hello,
I just installed a FUDforum, deleted: fudforum_archive, install.php, uninstall.php, upgrade.php and started to try it.
I have the following problem:
I did try to add Categories and "SubCategories" by Category Management System, but something went wrong - then I deleted some Categories and did try to add again Categories and "SubCategories".
The result now is a Category was duplicated by name, and one of duplicated Category contained a "SubCategory" - then I deleted all the Categories I could, but unfortunately the duplicated one with a "SubCategory" I can't edit nor delete - they just don't appear in Available Categories .... When I return to forum, I see these Category & "SubCategory", but when I go to Category Management System they don't appear in Available Categories
Can anybody help me about to remove these Category & "SubCategory", which don't appear in Available Categories ?
Thank you !
( May be the reason of above is I am using Bulgarian Alphabet for Categories, but the forum needs English Alphabet ? )

I think, I have been destroy my Forum-database, so I start to search for a solution about MySQL database.
I did not backup the database, but before Forum-installation on a Website, I did install it on my home PC2 under Linux Mint.
I did make a backup of working database at my home PC2, then uncompressed it from 'FUDforum_10_06_2016_10_16.fud.gz' to 'FUDforum_10_06_2016_10_16.fud', then uploaded it at the Website folder. The last step was to restore MySQL database - successful. So I have working database on my Website now.
I will be very careful, and will make backups often.